Ukraine’s underwater drones have broken through the long-held belief that submarines are unbeatable. On December 15, 2025, they struck a Russian Kilo-class submarine in a well-guarded Black Sea port. This marked the first confirmed hit by an underwater drone on a submarine in military history. Navies around the world now face tough questions about their defenses.
Submarines have ruled underwater battles for more than 100 years. They hide below the surface to attack ships from afar. Russia’s Black Sea Fleet has suffered heavy losses from Ukrainian drones since 2022. As a result, it pulled back about 300 kilometers from Sevastopol to Novorossiysk after Ukraine regained control of the key Crimean base. In Novorossiysk, four submarines, including three that can fire Kalibr cruise missiles, help Russia target Ukraine’s power plants. These attacks have cut off electricity and heat for millions of Ukrainians during the cold winter months.
The port in Novorossiysk has strong anti-aircraft systems and constant patrols. Still, submarines stay vulnerable when they stop for fuel, repairs, or crew swaps. Ukrainian spies kept close watch on the submarines’ movements and routines. They pinpointed weak spots at this base, which serves as Russia’s easiest submarine hub outside risky war zones.
The Piercing Strike
Ukraine’s Security Service sent out several Sub Sea Baby underwater drones for the mission. These uncrewed vehicles guided themselves through the narrow harbor paths using built-in navigation points. One drone exploded close to the back end of a Project 636.3 Kilo-class submarine tied up at the dock. The blast broke the concrete pier and let water flood into the submarine. The Security Service released video of the explosion’s effects, and Reuters confirmed its authenticity.
Evidence from Orbit
The next day, on December 16, satellite photos revealed clear signs of the attack. Images showed a 9-meter-wide hole in the pier right next to where the submarine had been docked. The damaged submarine sat lower in the water, listing to one side, which points to flooded sections inside. For contrast, a nearby Kilo-class submarine floated at its normal level. Experts at The War Zone reviewed photos from Vantor (once called Maxar Technologies) and Planet Labs. Their analysis backed up the strike’s severe damage.
Targeted Devastation
The explosion happened just 12 to 14 meters from the submarine’s stern, or rear section. It probably destroyed the propeller, rudder, and drive shaft, leaving the vessel unable to move on its own. Flooding at the back has taken this key Kalibr missile launcher out of action. Dmytro Pletenchuk, a spokesperson for the Ukrainian Navy, said the attack changes how people view naval fights. Submarines, it turns out, can fall to these kinds of drone strikes.
Moscow’s Evasive Response and Strategic Ripples
Russia’s Defense Ministry brushed off claims of serious harm. Officials said the submarines kept working as usual and that the drone missed its mark. Even so, they admitted an underwater unmanned vehicle had attacked. This clashes with their earlier statements that Ukraine did not have such weapons. Russia shared a video of the submarine, but it conveniently cut off the damaged stern area. This only raised more doubts.
The strike cuts Novorossiysk’s ability to launch Kalibr missiles by roughly 25 percent. The base now holds capacity for about 12 missiles instead of 16 across its remaining submarines. That relieves some strain on Ukraine’s power grid. The attack also highlights cyber weaknesses. Footage from the Security Service came from hacked security cameras at the base, hinting at live spying that helped guide the drones.
Fixing the submarine will prove tricky and risky. Dry-docking it for repairs could invite more attacks, while patching it up in the water would take a long time with limited parts available. A brand-new Kilo-class submarine runs $350 million to $400 million and needs years to build.
Ukraine’s shift to drones shows smart asymmetric warfare. Lacking strength in traditional forces, it uses low-cost uncrewed tools to hit expensive Russian targets. This echoes how airplanes once ended the era of giant battleships. NATO countries pay close attention. Ukraine’s success with offensive underwater drones could push Western militaries to build their own armed versions. That might spark a global race for underwater weapons.
Diesel-electric submarines must surface or dock for upkeep, making them easy prey. Crewless drones can sneak into protected harbors without detection. This attack warns that submarines no longer rule the seas alone. Navies must now strengthen their ports and update their strategies to counter fast-changing drone dangers.
Sources
Reuters: Ukraine says underwater drones hit submarine
The War Zone: Aftermath Of Ukraine’s Underwater Drone Attack On Russian Submarine Seen In Satellite Imagery
Naval Technology: Ukraine claims world-first underwater drone strike on Russian submarine
CNN: In a first, Ukraine says it struck Russian submarine in Black Sea
Defence Ukraine: 9-Meter Concrete Crater and Flooded Compartments: Satellite Image Confirms Critical Damage to Russian Submarine
Defense News: Ukraine’s first underwater drone strike caught on hacked camera